JPH10299447A - Oil return structure for crank shaft oil seal of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform smooth return of lubrication oil to an oil pan without flying. SOLUTION: A lower case 21 is coupled to the lower end part of a cylinder block and a crank shaft is supported by a bearing part 26. Half-division-form fit-in part 48 are formed in the rear end parts of a cylinder block and the lower case 21 and a cylindrical fitting-in part is formed at the periphery of the crank shaft. Oil seal is pressed in the fitting in part and a gap between the crank shaft and the fitting-in part is sealed therewith. An oil return groove 50 is formed in the coupling surface of the lower case 21 with the cylinder block and the inner side of the fitting-in part 48 is communicated with an oil passage 46 communicated with the interior of an oil pan. Lubrication oil leaking through the bearing part 26 is sealed by an oil seal and returned from the oil return groove 50 to the oil pan through the oil passage 46. Since no lubrication oil splashes on the crank part of the crank shaft, lowering of lubrication performance due to aeration is prevented from occurring by preventing flying of the lubrication oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil return structure of an engine crankshaft oil seal for sealing lubricating oil leaking from a bearing portion and returning the oil to an oil pan.

[0002]

2. Description of the Related Art An example of a conventional oil return structure of a crankshaft oil seal of an engine will be described with reference to FIGS. FIG. 9 shows the vicinity of the rear end of the crankshaft of the engine. In this engine, a lower case 3 is connected to a lower end of a cylinder block 2 in which a piston 1 is slidably fitted. The oil pan 4 is connected to the section. A crank shaft 7 is rotatably supported by a bearing portion 5 formed on the cylinder block 2 side and a bearing portion 6 formed on the lower case 3 side, and a rear end portion thereof extends to the outside. The piston 1 is connected to a crankpin 8 of the crankshaft 7 via a connecting rod 9. A flywheel 11 is attached to the rear end of the crankshaft 7 by bolts 10.

[0003] At the rear ends of the cylinder block 2 and the lower case 3, half-shaped fitting portions 12, 13 are formed adjacent to the bearing portions 5, 6, respectively. A substantially cylindrical fitting portion A is formed around the crankshaft 7. An oil seal 14 for sealing between the crankshaft 7 and the cylinder block 2 and the lower case 3 is press-fitted (fitted) into the fitting portion A.
Have been. In addition, a pair of oil return holes 15 (see FIGS. 10 and 11) penetrate the bearing portion 6 adjacent to the fitting portion 13 of the lower case 3 along the axial direction so as to face the end face of the oil seal 14. ing.

[0004] The oil gallery 16 of the lower case 3
The lubricating oil is supplied to the bearings 5 and 6 from the bearings 5 and 6 via an oil passage 17 to lubricate the journals of the crankshaft 7 and seal the lubricating oil leaking from the bearings 5 and 6 with an oil seal 14. , And is returned to the lower case 3 and dropped into the oil pan 4. Also, the fitting part of the lower case 3
By constantly holding the lubricating oil between the pair of oil return holes 15 in the oil seal 13, the oil seal can be
Prevents damage due to sticking of the 14 lip.

[0005]

However, the above-mentioned conventional oil return structure of the crankshaft oil seal of the engine has the following problems. Since the oil return hole 15 is open near the crank portion of the crankshaft 7, the lubricating oil flowing into the lower case 3 through the oil return hole 15 is applied to the crank portion of the crankshaft 7, and Because it scatters, air bubbles are easily mixed into the lubricating oil,
There is a possibility that the lubrication performance may be reduced by aeration. In addition, the provision of the oil return hole 15 reduces the strength of the bearing portion 6, so that the weight of the lower case 3 increases in order to secure the strength of the bearing portion 6.

The present invention has been made in view of the above points, and has as its object to provide an oil return structure of an engine crankshaft oil seal that can smoothly return lubricating oil to an oil pan without scattering. Aim.

[0007]

According to a first aspect of the present invention, there is provided an oil return structure for an engine crankshaft oil seal, wherein a lower case is connected to a lower end of a cylinder block. A crankshaft is supported by the bearing portion of the lower case and the bearing portion of the lower case, and the cylinder block and the lower case and the crankshaft are disposed adjacent to the bearing portion at the ends of the cylinder block and the lower case. An oil for mounting an oil seal to be sealed, and connecting an oil seal mounting portion of the cylinder block and the lower case to an oil passage vertically penetrating the cylinder block and the lower case on a coupling surface of the lower case with the cylinder block. A return groove is provided.

With this configuration, the lubricating oil supplied to the oil seal from the cylinder block and the bearing of the lower case flows through the oil return groove to the oil passage and returns to the oil pan. At this time, the lubricating oil returning from the oil seal to the oil pan does not reach the crank portion of the crankshaft.

According to a second aspect of the present invention, in the oil return structure of the crankshaft oil seal for the engine, in addition to the configuration of the first aspect, the oil passage is a blow-by gas passage for communicating the cylinder head with the oil pan. It is characterized by the following.

[0010] With this configuration, the lubricating oil supplied to the oil seal is returned to the oil pan through the oil return groove and the blow-by gas passage.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 8 shows the vicinity of the rear end of the crankshaft of the engine according to this embodiment. In this engine, a lower case 21 has a plurality of bolts 22 (only two are shown) at the lower end of a cylinder block 20. The oil pan 23 is connected to the lower end of the lower case 21 by a plurality of bolts 24 (only one is shown). As shown in FIGS. 6 and 7, a plurality of half-split bearing portions 25 (five in the drawing) are formed in the cylinder block 20. As shown in FIGS. 1 to 4, the lower case 21 is a substantially ladder-shaped member. The lower case 21 is opposed to the bearing 25 of the cylinder block 20 and has a plurality of half-shaped bearings 26 (5 in the drawing).
) Are provided. A crankshaft 28 is rotatably supported by a bearing 25 on the cylinder block 20 side and a bearing 26 on the lower case 21 via a bearing 27, and the rear end of the crankshaft 28 is connected to the cylinder block 20 and the lower case 21. It has been extended outside. A flywheel 29 has bolts 30
Installed by.

A piston 32 is slidably fitted in a cylinder liner 31 provided in the cylinder block 20, and the piston 32 and a crankpin 33 of a crankshaft 28 are connected to each other by a connecting rod 34. Crankshaft
28 is provided with an oil hole 35 for supplying lubricating oil to the crankpin 33 from a journal supported by the bearings 25 and 26. The lower case 21 is provided with an oil gallery (not shown) and an oil passage (not shown), as in the conventional example shown in FIG.
Further, the oil can be supplied to the crank pin 33 through the oil hole 35. In FIG. 8, reference numeral 36 denotes a water jacket, and 37 denotes a piston pin.

A bolt hole 38 disposed on both sides of each bearing 25 is provided in a joint surface of the cylinder block 20 with the lower case 21.
(Screw hole) and a bolt hole 40 arranged on the outer peripheral portion and the transmission mounting flange portion 39 are provided. The lower case 21 is opposed to the bolt holes 38 and 40 of the cylinder block 20 so that the bearing portion 26 Bolt holes 4 on both sides and outside and transmission mounting flange 41
2, 43 (through holes) are provided, through which bolts are inserted to couple the cylinder block 20 and the lower case 21 together. Further, a screw hole 44 for connecting the oil pan 23 is provided in the outer periphery of the lower end of the lower case 21.

In the cylinder block 20, an oil passage 45 (blow-by gas passage) penetrating vertically is provided outside the bolt holes 38 on both sides of each bearing portion 25 (excluding the front end portion).
Is provided. The lower case 21 includes
An oil passage 46 (blow-by gas passage) communicating with the oil passage 45 is vertically penetrated outside the bolt holes 42 on both sides of the 26 (excluding the front end portion). The interior of the cylinder head (not shown) communicates with the interior of the oil pan 23 through these oil passages 45 and 46, and lubricating oil is returned from the cylinder head to the oil pan 23, and blow-by gas is transferred from the oil pan to the cylinder head 23. To be sent to

The rear end of the cylinder block 20 has a bearing
A half-shaped (semi-cylindrical) fitting portion 47 protrudes adjacent to 25, and a half-shaped (semi-cylindrical) fitting is provided at the rear end of the lower case 21 adjacent to the bearing portion 26. A mating portion 48 is projected, and by joining these fitting portions 47, 48, a cylindrical fitting portion B (oil seal mounting portion) is formed around the crankshaft 28. I have. An annular oil seal 49 is press-fitted (fitted) into the fitting portion B, and its lip portion slides on the crankshaft 28 to seal between the cylinder block 20 and the lower case 21 and the crankshaft 28. It is supposed to. Further, an oil return groove 50 is formed on the coupling surface of the lower case 21 with the cylinder block 20 to communicate the inside of the fitting portion 47 with the oil passage 46 arranged at the rear end of the lower case 21.

3 is an oil strainer mounting portion, 52 in FIG. 4 and 53 in FIG. 7 are transmission mounting bolt holes, and 54 in FIG. 7 is a starter motor mounting portion.

Next, the operation of the embodiment constructed as described above will be described.

The lubricating oil stored in the oil pan 23 is sucked up by an oil pump (not shown), passes through an oil gallery (not shown) and an oil passage (not shown) of the lower case 21 and has a bearing portion. The lubrication is supplied to the journals 25 and 26 to lubricate the journal of the crankshaft 28. Lubricating oil leaking from the bearings 25 and 26 at the rear end of the cylinder block 20 and the lower case 21 is sealed by an oil seal 49, and an oil return groove is provided.
It flows into the oil passage 46 through 50 and falls into the oil pan 23. At this time, since the lubricating oil returning from the oil seal 49 into the oil pan 23 does not reach the crank portion of the crankshaft 28, it is possible to prevent the lubricating oil from being scattered and to prevent air bubbles from being mixed into the lubricating oil. Thus, a decrease in lubrication performance due to aeration can be prevented.

Oil return groove in fitting portion 48 of lower case 21
Since a small amount of lubricating oil is always held below 50, it is possible to prevent breakage due to sticking of the lip portion of the oil seal 49 at the time of starting the engine or the like. At this time, the depth D of the oil return groove 50 depends on the mounting angle of the engine (generally, the engine is mounted so as to be inclined in the rotation direction of the crankshaft 28).
By setting (see FIG. 2), an appropriate amount of lubricating oil can always be held in the fitting portion 48.

Further, the oil return groove 50 can be easily formed so that it can be formed, for example, at the time of casting of the lower case 21, and the strength of the bearing portion is less reduced compared to the conventional oil return hole. Therefore, the weight of the lower case does not increase in order to secure the strength of the bearing portion.

In the above embodiment, the fitting portions 48 and 49 of the cylinder block 20 and the lower case 21 are respectively provided.
Bosses 55 and 56 are formed on both sides of the
Bolt hole 57 (screw hole) and bolt hole 58 (through hole) at 56
May be provided, and the bosses may be connected by bolts (not shown). In this case, since the connecting surfaces on both sides of the fitting portions 48 and 49 are connected to each other with a sufficiently large surface pressure by bolts, the sealing performance of the fitting portions 48 and 49 can be improved, and the fitting portions 48 and 49 can be improved. Oil leakage from 48 and 49 can be reliably prevented.

[0023]

As described above in detail, according to the oil return structure of the engine crankshaft oil seal according to the first aspect of the present invention, the lower case is provided with an oil return groove on the connection surface with the cylinder block, and the cylinder is provided with the oil return groove. By connecting the oil seal mounting portion of the block and the lower case to the oil passage vertically penetrating the cylinder block and the lower case, the lubricating oil supplied to the oil seal from the bearing portion of the cylinder block and the lower case flows through the oil return groove. The oil passes through the oil passage and returns to the oil pan. At this time, since the lubricating oil returning from the oil seal to the oil pan does not reach the crank portion of the crankshaft,
It is possible to prevent the lubricating oil from being scattered, prevent bubbles from being mixed into the lubricating oil, and prevent a decrease in lubricating performance due to aeration.

According to the oil return structure of the engine crankshaft oil seal according to the second aspect of the present invention, the oil passage is formed as a blow-by gas passage for communicating the cylinder head with the oil pan, thereby supplying the oil to the oil seal. The lubricating oil is returned to the oil pan through the oil return groove and the blow-by gas passage.

[Brief description of the drawings]

FIG. 1 is a top view of a lower case according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a partial cross section taken along line CC of an oil return groove of the lower case in FIG. 1;

FIG. 3 is a bottom view of the lower case of FIG. 1;

FIG. 4 is a side view showing a rear end of the lower case of FIG. 1;

FIG. 5 is a longitudinal sectional view of the lower case of FIG. 1;

FIG. 6 is a bottom view of a cylinder block connected to the lower case of FIG. 1;

FIG. 7 is a side view showing the rear end of the cylinder block of FIG. 6;

FIG. 8 is a longitudinal sectional view of the vicinity of a rear end of a crankshaft of the engine according to the embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of the vicinity of a rear end of a crankshaft of a conventional engine.

10 is a top view of the lower case of the engine shown in FIG. 9 in the vicinity of a rear end of a crankshaft;

FIG. 11 is a side view showing the rear end of the lower case of FIG. 10;

[Explanation of symbols]

 20 Cylinder block 21 Lower case 23 Oil pan 25,26 Bearing 28 Crankshaft 45,46 Oil passage (blow-by gas passage) 49 Oil seal 50 Oil return groove B Fitting part (oil seal mounting part)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02F 11/00 F02F 11/00 J F16C 33/10 F16C 33/10 Z

Claims (2)

[Claims] 1. A lower case is coupled to a lower end of a cylinder block, a crankshaft is supported by a bearing of the cylinder block and a bearing of the lower case, and the cylinder block and the cylinder are disposed adjacent to the bearing. At the end of the lower case, an oil seal that seals between the cylinder block and the lower case and the crankshaft is mounted, and at the joint surface of the lower case with the cylinder block, the oil seal of the cylinder block and the lower case is mounted. An oil return structure for an engine crankshaft oil seal, wherein an oil return groove is provided for communicating a portion with an oil passage vertically passing through the cylinder block and the lower case. 2. The oil return structure of an engine crankshaft oil seal according to claim 1, wherein the oil passage is a blow-by gas passage that connects the cylinder head to the oil pan.